1
Discussion paper No. 2011–3
Climate gas emissions from food systems – use of LCA analyses
Refsgaard K
12, H Bergsdal
3, J Pettersen
4and H Berglann
51Norwegian Agricultural Economics Research Institute Post box 8024 Dep
NO-0030 OSLO NORWAY
Corresponding author: karen.refsgaard@nilf.no This version: August 2011
(Please do not quote without permission from the authors.)
1 Norwegian Agricultural Economics Research Institute
2 Corresponding author
3 MiSA, Trondheim
4 MiSA, Trondheim
5 Norwegian Agricultural Economics Research Institute
2
Copyright © by the Author(s). All rights reserved. Readers may take verbatim copies of this document for non- commercial purposes by any means, provided that this copyright notice appears on all such copies.
Papers in this series are meant for stimulating discussions. The authors would welcome all kinds of responses to this paper. The interpretation and conclusion in this paper are those of the author(s).
This discussion paper may have been submitted to a journal and have entered the journal’s review process.
Should the journal decide to publish the article the paper no longer will have the status of a NILF Discussion Paper and will be withdrawn from this website. From then on a link will be made to the journal in question referring to the published work and its proper citation.
Copies of this discussion paper are available at
http://www.nilf.no/publikasjoner/Discussion_Papers/2011/dp-2011-03.pdf
3 Motivation6
The evolution of conventional agricultural production practices to satisfy the demand for food is argued by many to be one of the major driving forces behind an increased environmental impact and resource consumption in Western households. Current agricultural production contributes heavily to emission of the greenhouse gases CH4, N2O and CO2 – as has been emphasized both by international organisations (IPCC, UNEP, IAASTD, FAO) and by the research community (Tukker et al. 2006; Tukker and Jansen, 2006). Data from Eurostat (2010) show, that the relative importance of agriculture in terms of its contribution to the overall level of greenhouse gas emissions in the EU was 9.2% in 2007 with 462.2 million tonnes of CO2-equivalents. A study on Europe coordinated by the EU Joint Research Centre (EIPRO study) shows that food and drink is responsible for 20% to 30% of the environmental impact of private consumption in the EU, with meat and dairy products contributing most.
Data from the 90-ies in Denmark (Forbrugerstyrelsen 1996) and the Netherlands (Kramer et al. 1994, 1999) show that consumption of food has a 20-35% share of the total energy use in a household.
According to Bye et al. (2010) Norway had a total emission of 50.8 mill tonnes CO2- equivalent in 2009 of which 4.8 mill tons (9%) came from the agricultural sector (48% CH4, 41% N2O and 10% CO2). Greenhouse gas emissions from agricultural practices are primarily in the form of nitrous oxide (N2O) resulting from the application of fertilisers and manure, tillage of moors and nitrogen emission, or in the form of methane (CH4) that results, among other things, from livestock emissions, stored animal manure and finally CO2 from fuel for agricultural machinery. In contrast to most other sources, there are relatively low levels of carbon dioxide emissions resulting from agriculture practices; rather, agricultural land and forests generally sequester (hold) carbon reserves and help to reduce levels of carbon dioxide in the atmosphere. Statistics Norway provides annual numbers for the direct emission of greenhouse gases from each sector in the Norwegian economy (Statistics Norway 2010).
However, if we include the emissions arising indirectly from manufacturing of mineral fertilizer, and carbon-losses from arable land management and tillage of moor, the total emission from agriculture rises by some 62% to around 7.8 mill tons CO2-equivalents (Trømborg et al. 2008). In addition, carbon fixation in grassland (Swensen et al., 2010) is a major sequestration source to consider. Outside the farm gate food processing, transport, storage and shopping structures may also be relevant to consider (Coley et al. 2009). It is therefore of questionable merit to look at the impact of agricultural production purely from a sectoral point of view.
Historically most industrialized countries have experienced a shift in energy sources from animals to tractors, and hence from biomass 'fuel' to fossil fuels, increasing overall energy use over time among other through a change in the use of fertilizer from recycling natural fertilizer such as manure and night soil, towards chemical fertilizer, which is industrially mined and processed (Neset and Lohm 2005; Pimentel et al., 2005; Hall et al 1992). The two major substitutes for fossil energy in agricultural production are solar and human energy (Refsgaard et al. 1998). The sun and the fossil fuels differ in their patterns of scarcity. Radian- energy from the sun is practically infinite in total amount (stock), but it is strictly limited in its flow rate. Conversely, energy stored in fossil fuels and minerals is strictly limited in its total amount in a very long perspective (stock), but relatively unlimited in its flow rate-that is, we can use it up at a rate largely of our own choosing (Daly and Cobb, 1989). Solar energy is
6 This work is carried out through the research project “Socio-economic and environmental impacts of organic farming” running from 2008 to 2011, funded mainly by The Research Council Norway and with additional funding from Oikos, the County Governor Sør-Trøndelag and KSL Matmerk.
4
indirectly brought into the agricultural production system through crop production, with land and plants acting as solar collectors. The highest quality soils require less human and fossil energy inputs per unit of food produced than the poorer soils. Yet food production can be increased markedly in the short term by investing more energy (Jones, 1989; Hall et al., 1992;
Pimentel et al., 1994). It is therefore important to not only focus on the emission of CO2 but also on the associated land use. Halberg et al. (2005) support this view in their comparison of different types of assessment tools with the purpose of determining the environmental impact of various livestock production systems at farm level including LCA methodology. They mention that most indicator tools present the environmental impacts per hectare and most systems include only the emissions from the farm itself, but that some environmental impacts, e.g. greenhouse gas emission, are of a global nature and therefore the emission per unit produced is as relevant from a global, environmental perspective as the emission per hectare.
Organic farming7 is an approach to agriculture that emphasises environmental friendly production practices and sustainable resource use and which utilises the market to help support these objectives and compensate for the internalisation of externalities (Lampkin 2003). Relative to conventional farming8, however, this production system requires more land for the same amount of food output9. To compare these production systems with respect to discharges of greenhouse gases it is therefore of more interest to use CO2–equivalents per unit produced, rather than emissions per hectare, as the relevant indicator. Studies focusing on this comparison have already been conducted for some important food products in various countries (see references in Mondelaers et al., 2009) using life cycle assessments (LCA).
World leaders called for Life cycle assessments (LCA) at the 2002 World Summit for Sustainable Development in Johannesburg, to promote sustainable patterns of production and consumption. LCA is a tool used to assess the environmental impacts of production systems and services, accounting for emissions and resource uses during production, distribution, consumption and disposal of a product (Carlsson-Kanyama et al. 2003, Brentrup et al. 2004, Hertwich 2005). Today LCA is an internationally standardised tool (ISO, 1997, 2006) although questions related to system delimitation, and general principles can be discussed.
Since the World Summit in 2002 several LCA analyses have been conducted around the world for a number of typical consumer products and LCAs for food have become more common. Milk, bread, pork and beef are the most comprehensively studied food products (e.g. Møller and Vold, 1995; Weidema et al., 1995; Andersson et al., 1998; Andersson and Ohlsson, 1999; Moilanen, 1999; Cederberg and Mattsson, 2000; Berlin, 2002; Høgaas Eide, 2002; Ziegler et al., 2003; Halberg et al. 2005, Weidema et al 2008, Cederberg et al. 2009. A study by Saunders et al. (2006) conducting a LCA for some key New Zealand food exports to the UK comparing them with the best alternative source for the UK market was found quite controversial as it concluded that the energy costs were much higher for lamb produced in the
7 Organic agriculture is distinct from conventional agriculture through alternative agricultural practices, world view and values (Watson et al. 2006) and IFOAM recognizes four basic principles of health, the ecological principle, the principle of fairness and the principle of care being the roots from which organic agriculture grows and develops (IFOAM 2005 cited in Watson et al 2008:2). Inherent within those principles is the idea of farming systems and the links between the production methods and the health of the consumer. For an overview of organic rules and certification in EU, European countries and the US see
http://organicrules.org/custom/completestandard.php.
8 As in Nemecek et al. (2011) we define conventional farming in this study as a mode of production not respecting the organic farming rules (see link in footnote 1). The agricultural system’s main goal is to achieve high yields and a high economic output.
9 Meta-analysis’ by Mondelaers et al. (2009) and by Badgley et al. (2007) report an average
organic/conventional yield ratio of respectively 83 and 91 per cent for developed countries for all crops.
5
UK than for NZ lamb. This was due to several causes like cooling facilities, type of energy used, type of transport medium etc. (Kemp et al. 2010). The lesson learned from this example is that our analyses have to be conducted for the whole system, from ‘cradle to grave’.
It is therefore not obvious how the emission of climate gasses are influenced by a change in production intensity, as reduced yields might counterbalance any energy savings from reducing external inputs. Any restrictions imposed in a part of a farming system might be substituted for in other parts of the system by the farmer. Therefore, it is an interesting and complex question whether less intensive farming systems have lower climate gas emissions than more intensive food systems.
Purpose
This article aims to present a systematic overview of production of four different and common agricultural products and their emissions to air of CO2 and associated land use. This includes analysis of the environmental consequences with respect to CO2 emission and land use of food production and for different food production systems to be able to answer questions like
a. What are the large emission processes?
b. How does the emission vary with product and with production system?
c. What is the trade-off with land?
d. How does the data from Norway compare to other studies?
e. What are the variations and the uncertainties?
f. What is the potential for reduction of CO2-emissions?
Methodology and data
Models for Norwegian farm based on data from Farm Account Data Analyses (FADN) producing milk, meat and grain under different production systems were analysed according to their emission of CO2-equivalents from CO2, CH4 and N2O. The assessment was carried out within the framework of life cycle assessment (LCA) to include both direct farm emissions as well as upstream indirect effects from production of inputs to farm activities.
The product life-cycle covers all processes from extraction of raw material, via production, use, and final treatment or reuse (Wenzel et al. 1997, Guinée 2001, Baumann and Tillman 2004, ISO 2006). The reader is referred to these references for a more general introduction to LCA methodology.
In addition to the emission of CO2, CH4 and N2O also the use of land is analysed as this is a major substitute for fossil energy and other resources in agricultural production. Further higher quality soils require less human and fossil energy inputs per unit of food produced than poorer soils. It is therefore important to not only focus on the emission of CO2 but also on the associated land use and the yield potential.
Data sources
The objective of this work is to represent average Norwegian farm production rather than norm-based production with more regulated and specific characteristics. Further using data from whole farms instead of disaggregated data from trials etc. is important because simple relations between individual input factors, processes on the farm, climate emission and land
6
use cannot be expected as input factors and processes may substitute each other (Refsgaard et al. 1998). By using data from whole farms we are able to track the substitution and the
‘lacking’ resource use due to integrated production processes.
Agricultural production in Norway varies considerably with respect to farm size, composition of production output, geographical and climatic conditions, and farming practices. Farms from the account statistics are grouped according to main production output(s) into model farms representing different production systems, different farm sizes and different regions in Norway. The aggregation into model farms is carried out on an annual basis by the Norwegian Agricultural Economics Research Institute, and includes 27 different farm types of which 15 are on a national level and the remaining are subsets representing different regions.
The models are based on account statistics from annual surveys of more than 800 farms in Norway (Driftsgranskninger i jord- og skogbruk). In our analyses the following model farms have been used for the years 2005-2007, see Table 1.
Table 1: Model farms used for analyses of CO2-emissions
Acro-
nym Name Production system Size No of farms
as source Data covering Ref1 Referansebruk no 1 Milk and beef
meat 20 annual cows 341 Country
Ref2 Referansebruk no 2 Grain 333 daa 88 Country
Ref5 Referansebruk no 5 Pork and grain 46 sows,
357 daa grain 38 Country
Ref7 Referansebruk no 7 Potatoes and grain 103 daa potatoes, 335 daa grain
13 Country Ref8 Referansebruk no 8 Beef cattle /
suckler cows 25 suckler cows 33 Country
Ref10 Referansebruk no 10 Chicken and
plant products 80383 chicken
slaughtered 15 Country
Ref11 Referansebruk no 11 Organic milk and
beef 20 annual cows 23 Country
Ref14 Referansebruk no 14 Milk (the 40 largest)
40 annual cows 40 Country
Org
W Modelled farm by Agricultural Advisory Service (SørØst)
6 years crop rotation with green manure
Green manure, wheat, oat w/under culture, oat/peas, rye w/grass, green manure
Experiences from extension service
Eastern Norway
Source: Adapted from ”Referansebruksberegninger”
Model farms covered in this study are listed in Table 1. For each farm type, the following inventory approach is used.
Physical units for intermediate farm inputs and production:
Physical units for intermediate farm inputs and production are calculated from monetary value for reference farms, based on unit price (Budsjettnemnda for jordbruket 2008b, Budsjett- nemnda for jordbruket 2009b). Various other costs and income are also available but were not used in this study. Both unit prices, and the volumes of intermediate inputs are averages for the period 2005-2007
Data for model farms and prices are gathered and averaged for the last three years’ data sets (2005-2007) to provide more robust inventory data and account for price fluctuations for both inputs and outputs, fluctuations in production yield due to weather and climatic conditions, changes in production output composition and crop rotation.
7
Construction of the LCA model is significantly simplified by the standard format used for reference farms. Both intermediates and products are listed and registered in a strict format, enabling consistent and easy implementation and update of model values.
Table 2 shows an example of registered inputs to, and Table 3 shows outputs from, farm production. In this case the example is dairy farm. For model farms with livestock, feed concentrates is the largest purchase. These input categories represent all types of chemical fertilizers, feed concentrate composition and so on. Assumptions about composition and manufacturing of the various inputs to production are provided in Appendix A.
In the case of a specialized cereal farm the main outputs being barley, wheat and oat all together making up almost 90 % of total output in monetary units. The largest purchases are fertilizers, fuel and seed grain. The remaining posts are made up of products that are not descriptive of cereal production, but reflect that farms often also have a small production of other agricultural products.
The statistical accounts report only monetary flows entering and exiting the farm gate, i.e.
internal production and use that are not represented by a purchase or a sale cannot be separated out from the data sets. This implies that for example internal production and use of fodder is covered indirectly by its share of the purchases, but the share cannot be distinguished.
Organic cereal production
Organic cereal production is not covered by any of the reference farms, and must therefore be modelled separately. An organic grain/cereal production without animals was defined based on information from the Agricultural Advisory Service (LF SørØst). This Agricultural Advisory Service is located at Østlandet, the area receiving 68% of the subsidies for organically grown grain in 2008 (Agricultural Authority 2009, NILF 2009). This is the area most common with a crop rotation without animal husbandry. The data from the Agricultural Advisory Service are based on knowledge from farm production in their area.
8
Table 2: Registered inputs to farm production. An example of a dairy farm
Source: Adapted from Budsjettnemda for jordbruket 2007; 2008a and 2009a
Table 3: Registered outputs from farm production. An example of dairy production.
Source: Adapted from Budsjettnemda for jordbruket 2007; 2008a and 2009a Direct and indirect emissions from fertilization and husbandry
Direct and indirect emissions from fertilization and husbandry are modelled using an adaptation of the national greenhouse gas accounts for agriculture, with Tier 2 resolution for most factors (Sandvik, 2009). Emissions are normalized per animal, per mass of fertilizer N and P applied, and per volume of manure; see documentation elsewhere (Pettersen 2010) Fertiliser use and stock of animals are reported for each reference farms, and these are used directly in the inventory model without adjustment for organic or conventional feeds.
9 Manufacturing of input factors
Manufacturing of input factors is modelled using the Ecoinvent database, with some modifications for the most important inputs, most notably fertilizer production and feed concentrate production which are modified according to Norwegian production and use (see Appendix A).
Allocation for farm operations
Allocation for farm operations is based purely on price of production. Economic allocation is used for distributing the inputs between the different outputs, i.e. if a farm output represents 25 % of total income from sales (subsidies excluded), this output is assigned 25 % of each input to the farm and the corresponding impacts from production of these inputs. This implies that some outputs are also assigned a share of inputs that are not used in their production.
Physical inputs to farm production for a model farm are presented in Table 2. Some inputs are marked to indicate that they are not modelled directly. This concerns input categories containing miscellaneous products with unknown composition, and mostly with a small share of the total value of inputs. A notable exception is the use of pesticides which makes up a considerable share of the value of inputs for model farms with cereal production. Rather than excluding these input categories and systematically underestimate emissions from production of inputs, they are accounted for by distributing their value on the other input categories according to their share of total input. Miscellaneous input categories are therefore included in a simplified but consistent manner.
Issues in the inventory approach
We assume that organic and conventional animals have the same direct and indirect emissions, i.e., no adjustment for different feeding practices or treatment of manure.
However, organic fed cows eat more grass, thereby should have more enteric emissions
The reference farm data do not identify whether manure is transferred from conventional to organic farming. This may be interpreted as allocating downstream emissions always to the origin of the manure, i.e., to the owner of animals. However, manure application is a major emission source for organic farming and should be included as an intermediate in their production.
The farm level scope used makes it difficult to make product-by-product comparison for typical multi-output products, as we cannot identify use of intermediates to specific products.
Manure management is an important aspect of greenhouse gas emission from husbandry.
Our inventory model relies on national averages for the direct and indirect emission from manure storage and application, and should be made more detailed to allow estimation of the effect of using different management practices.
Table 4: Average yield levels for dairy production and plant production systems
Grass domestic
Grain domestic
Feedstuff
import Milk
Feed Units per
ha kg per ha kg per ha kg per cow
Dairy Conventional 3 500 6 064
Organic 3 000 5 234
Grain Conventional 4 720 5 000
Organic 1 965 5 000
Sources: Budsjettnemda for jordbruket 2007, 2008a, 2009aMcIntyre et al (2009), IIASTD-report, Forsøksringen SørØst
10 Land use
Land use
Land use is modelled in a simplistic approach, only including the direct land use in farming but including land both from imported as well as national produced inputs. These calculations are carried out outside the life cycle analyses operations.
Average yield data from the years 2005-2007 for reference farms are used for calculating the land use for production of 1 kg of each of the products grain and potatoes as well as for the land use for fodder used as input in the dairy and beef production. For the imported feedstuff FAO-data from the IIASTD-report with 5,000 kg of wheat per hectare as a rough estimate for ten NAE countries. For the organically grown grain the yield levels are based on information from the Agricultural Advisory Service (LF SørØst) as they are located in the area most of the organically grown grain is produced (68% of the area in 2008).
The yield levels (for both plant production and for dairy production) under different conditions for the different products are shown in Table 4.
Results
The emission of CO2-equivalents and the use of land for food production until farm gate
In Figure 1 the emissions to air of CO2-equivalents is shown both per kg food and per mcal.
The CO2-emission per kg food is much higher for the animal products than for the plant products. However, when the energy content of food is considered the differences are reduced heavily especially between meat and milk. The emission from meat is from 6 to 9 CO2-eq per mcal, from milk it is 3.58 – 4.09 kg CO2-eq per mcal milk, while production of wheat only contributes with from 0.14 - 0.24 kg CO2-eq per mcal. For all products the average numbers for conventionally products are from 30% to 70% higher than for the organically products with the lowest difference for beef.
For land use we see a different picture. Organically produced food has in average 10% to 70%
higher land use of land than conventional produced food with the lowest difference for beef.
Within each type of production system the land use for animal products are higher than for plant products with around 16-17 m2 per mcal meat compared to around 1 m2 per mcal wheat.
Comparing organic production with conventional production shows that the CO2-emission in general is lower for organic products than for conventional products, and that land use is higher. The relative difference between the production systems is about the same but
‘opposite’ for each of the products.
11
Figure 1: Emission of CO2-equivalents for different food products in Norway. Average numbers based on Referansebruk10
Figure 2: Land use for different food products in Norway11
10 Average numbers for conventionally produced food is composed as a weighted average of the different Referansebruk. For beef MF1 counts 76% (15.1 CO2-eq of which 8.1 is direct emission at farm gate), MF8 counts 9% (34,1 CO2-eq of which 20.1 from direct at farm gate) and MF14 weighs 15% (15.06 kg CO2-eq at farmgate).
11 Average numbers for conventionally produced food is composed as a weighted average of the different Referansebruk. For beef MF1 counts 76% (15.1 CO2-eq of which 8.1 is direct emission at farm gate), MF8 counts 9% (34,1 CO2-eq of which 20.1 from direct at farm gate) and MF14 weighs 15% (15.06 kg CO2-eq at farmgate).
0,00 5,00 10,00 15,00 20,00
potatoes, conv wheat, conv wheat, org milk, conv milk, org beef, conv beef, org
CO2-eq
product
Emission of CO2-eq for products at farm gate
kg CO2-eq per mcal kg CO2-eq per kg product
0 10 20 30 40
potatoes, conv wheat, conv wheat, org milk, conv milk, org beef, conv beef, org
m2
product
Land use for products at farm gate
m2 per mcal m2 per kg product
12
Composition of CO2-eq emissions and variation between different production systems
There is a variation in the CO2-emission by producing each of the analysed products depending on type of production system. In Figure 3, 4 and 5 the contribution of the different sources of inputs for manufacturing and production for different production systems can be seen.
In Figure 3 we see results from wheat production at six different ‘Referansebruk’ with a variation from 0.34 to 0.72 kg CO2-equivalents per kg wheat at farm gate. The mineral fertilizer including both manufacturing and fertilizing contribute with the major part of the CO2-emission from the conventional production systems without animals (Ref7Pt, Ref7W, Ref2W) while feed concentrates is a large source for the production systems producing plants in a production system with animals. However the feed concentrates is indirectly also having mineral fertilizer as their main source for CO2-emission. The organic wheat production using green manure in two out of six years in the crop rotation has its main source for CO2-emission from green manure.
Figure 3: The sources for CO2-eq emissions from production of wheat and potatoes in different production systems
In Figure 4 we see that the largest main contributor to CO2-emission from milk is the direct emission from husbandry production, i.e. the CH4 and N2O from digestion and manure contributing with 54% of the total emission at farm gate from conventional production and 71% from organic production. The difference between the three analysed production systems is mainly the mineral fertilizer contributing with climate emission from processing of nitrogen through CO2 and N2O / NH3 and from fertilizing on the farm through N2O for the two conventional production systems.
0,000 0,200 0,400 0,600 0,800
Ref2W grain Ref5W pig & grain Ref7W potatoes & grain Ref10W chicken & plants OrgW grain Ref7Pt wheat & potatoes
CO2-eq per kg wheat/potato Production system
Wheat and potato production
Mineral fertilizing
Mineral fertilizer, manufacturing Fertilizing, green manure
Seed, limestone and grass meadow Enteric and manure, livestock Feed concentrates
Diesel Electricity
13
Figure 4: The sources for CO2-eq emissions from production of milk in different production systems
Meat production varies heavily depending on whether it is beef, pork or poultry. In figure 5 we see that all light meat (chicken and pork) have much lower emission of CO2-equivalents, 2.73 - 4.5 kg CO2-eq per kg product, than beef production. The CO2-emission from beef meat produced in combination with milk (Ref1B, Ref11B and Ref14B) emits less than 50%, 11-15 kg CO2-eq per kg beef, is only half the CO2-emission when produced from suckler cows, 34 kg CO2-eq per kg beef meat.
Figure 5: The sources for CO2-eq emissions from production of meat in different production systems
0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8
Ref1M milk & beef Ref14M milk & beef (large) Ref11M org milk & beef
CO2-eq per kg milk Production system
Milk production
Mineral fertilizer, manufacturing Mineral fertilizing
See, limestone
Enteric and manure, livestock Feed concentrates Diesel Electricity
0,00 10,00 20,00 30,00 40,00
Ref1B milk & beef Ref8B beef Ref11B org mil & beef Ref14B milk & beef (largest) Ref5Pk pig & grain Ref10C chicken & plants
CO2-eq per kg meat Production system
Meat production
Mineral fertilizer, manufacturing Mineral fertilizing
See, limestone and grass meadow Enteric and manure, livestock Feed concentrates Diesel
Electricity
14
Comparison of our results with results from across the world
Various studies have compared the environmental impacts of conventional, integrated and organic farming. The following short review concentrates mainly on LCA studies. Most of the publications cited came to the conclusion that the environmental impacts per cultivated area are reduced in organic farming systems as compared to conventional agriculture. In an evaluation per product unit, the authors found lower, similar or higher impacts of organic farming, depending on the production system, site effects and differences in management intensity. The following overview concentrates on the evaluation per kg of product.
Many studies report a lower energy demand per product unit, e.g. Refsgaard et al. (1998) and Cederberg and Mattsson (2000) for organic milk production, but the energy demand can also be similar (Bailey et al., 2003) or higher (Kramer et al., 2000) than for conventional farming.
A conversion to organic farming would increase energy efficiency of Danish agriculture (Dalgaard et al., 2001). Lötjönen (2003) showed that machinery operations can use up to twice as much energy on organic than on conventional farms – while the energy efficiency analyzing farm production systems in Denmark as a total was better in organic farming than in conventional farming for both grass, grain and milk production in Refsgaard et al. (1998).
For the global warming potential, the results are less clear. Organic Irish suckler-beef production had lower emissions of greenhouse gases than conventional production per area and per product unit (Casey and Holden, 2006). Also organic apples had a lower global warming potential (Milà i Canals et al., 2001), while organic baby food (Mattsson, 1999) or organic milk (De Boer, 2003) and various other products (Williams et al., 2006) showed higher emissions per product unit.
Many studies investigated only the average differences between the systems. However, there is also a considerable variation within a given farming system (Mouron et al., 2006; Rossier and Gaillard, 2001; van der Werf et al., 2009). The cited studies compare organic, integrated or conventional farming in a series of case studies. Depending on the actual management intensity, farming context, climate and soil conditions, crops, etc. they come to partly contradicting conclusions. None of these studies make a systematic evaluation of a series of farming systems or crops that would allow drawing conclusions for Swiss organic and integrated farming systems and furthermore most of these studies focused on single crops and did not consider the impact categories biodiversity and soil quality that are of particular relevance for organic farming.
As mentioned above, various studies have carried out ‘cradle to grave’ comparisons of the environmental impacts of conventional and organic farming. Meisterling et al. (2009) investigated wheat flour production finding the organic method to be superior, while Nemecek et al. (2011, Switzerland) found that the two production systems also could be similar in that respect.
As Hospido et al. (2010) argue, the environmental impact from animal and vegetable products often differs by a factor of 10. Our results also show large differences in impact between animal and vegetable products, but the difference is much larger, around 20 between grain and milk and around 40 between grain and beef, when comparing nutrient value instead of comparing kilo. Swedish studies carried out by Cederberg et al. (2009) report 20 kg CO2-eq per kg carcass weight at retailer, compared to 17.7 kg CO2-eq per consumed kg meat for Norwegian conventional production. Nguyn et al. (2009) report that GHG-emissions from primary production of beef in Europe are in the range of 15-27 kg CO2-eq kg per kg carcass
15
weight at farm-gate, with beef produced as by-products from milk production in the lower end of the range and beef produced in “cow-calf systems” in the upper end. From Nguyen et al.
(2010) studying four beef production systems – three from intensively reared dairy calves and one from suckler herds we find the following results. Analysis of the contributions from production of 1 kg beef meat (slaughter weight) to global warming, acidification, eutrophication, land use and non-renewable energy use were lower for beef from dairy calves than from suckler herds (16.0–19.9 versus 27.3 kg CO2-eq, 101–173 versus 210 g SO2-eq, 622–1140 versus 1651 g NO3-eq, 16.5–22.7 versus 42.9 m2 per year, and 41.3–48.2 versus 59.2 MJ, respectively).
Cederberg et al. (2009) calculated 1.08 CO2-eq per kg milk at farm gate in 2005 compared to 1.65-1.88 CO2-eq per kg milk from our studies. When dividing the emissions between milk and beef, Cederberg et al. used an allocation factor of 85 % to milk and 15 % to meat (culled cows and surplus calves further to be raised in beef production), In our calculations the economic contribution being in average 67% to milk and 25% to beef in conventional and 74% to milk and 17% to beef in organic combined dairy production. Weidema et al. (2008) have calculated the CO2-eq emission from Danish milk production to be 2.4 CO2-eq per kg and 28.7 CO2-eq for dark meat.
Floren et al. (2005) have calculated the emissions from Swedish studies from 2000 and for about 20 case study farms to be about 0.98 kg CO2-eq per kg conventional milk and 0.95 CO2-eq per kg organic milk.
Analyses of the variations and of the uncertain data
There is a great deal of uncertainty related to calculations of climate gas emissions which is due to different aspects including among others:
Uncertainty related to the coefficients used – among other related to the use of estimates for indirect and direct emission from husbandry and fertilization being major emitters.
The generalisation of coefficients like CH4 emission from the dairy production related to type of feeding regime
The system boundaries – which are not uniquely defined in the referred studies.
The system boundaries – which are complex to define as they involved decisions about alternative possibilities for use of inputs and outputs.
Variation due to our data material due to weather and wind, farm management etc.
The allocation issue in combined production Direct emission from milk and meat from ruminants
In calculating the direct emission from milk and beef meat production we have used constant coefficients for CH4-losses from enteric fermentation12 and from animal manure in stable and storage as well as for N2O from animal manure. The emission of CH4 from the management of manure is dependent of type of storage, spreading and treatment. Also the loss of N2O (indirectly through NH2) and directly from manure management is dependent of type of storage and spreading. However these losses has a much lower contribution to the direct emission than methane and will not be further investigated here.
12 143 kg CH4-loss/dairy cow/year (Volden and Nes, Sundstøl and Mroz 1988, IPCC 1997, Salmo (ed) 2009, Pettersen 2010)
16
Trømborg et al. (2006) have made estimations analysing the variations in enteric CH4- emission related to production intensity13. Using the estimates by Trømborg et al (2006) a decrease in yield on 1 000 kg per cow would imply a 10% increase in CH4-emission per kg milk14. The result is a decrease in difference between milk produced organically and milk produced conventionally with about 100 000 tons CO2-equivalents for the total production of 1 500 mill l milk15.
Mineral fertilizer
The other large contributor to CO2-emission from conventional production of all farm products and contributing to a difference to organic production is manufacturing and application of mineral fertilizer. It contributes 21% of the total emission for milk and 69% of the total emission for wheat. In our calculations the coefficients for CO2-emission from fertilizer processing are based on the current technology from Yara16, being about the most energy efficient technology available. This implies that by using other technologies with less efficiency the CO2-emission will increase. The fertilizing coefficients are very uncertain and therefore rough estimates17.
Carbon sequestration in soil
Changes in the soil carbon pool have not been accounted for. Riley (pers. comm. in Trømborg et al. 2006) has calculated the loss from arable land in the Eastern part of Norway to about 2 000 kg CO2 per ha. The total loss from arable crops can then be estimated to – for all cropland (domestic and imported) about 1.73 mill tonnes CO2-eq for conventional production and 1,69 mill tonnes CO2-eq for organic production. Danish experiences (Petersen et al. 2006) are that
‘livestock-crop rotations’, including the area for feed-cereals, in total will have a zero net impact on soil carbon pools (grass based and manure rich crop rotations increase C-pool, whereas cereal production decreases).
DISCUSSION
In this paper, we have looked at emissions of CO2--equivalents arising from the three main sources in agriculture, CH4, N2O and CO2. All three sources contribute to emission from agriculture and production of food but the contribution from agriculture differ according to production system like organic versus conventional combined dairy and beef meat production and between beef meat production in combination with milk production versus in suckler cow production. There are also large differences between production of food energy from cereals compared to food energy from beef meat compared to food energy from milk.
Life Cycle Assessments (LCA) has been used as the methodology to analyse the differences between production systems and between different types of food for emission of CO2- equivalents. In this paper the LCA include the emissions arising from manufacturing of inputs like mineral fertilizer as well as the production on the farm until farm gate. In addition we
13 145,8 kg CH4-loss per 6000 kg milk per year (Trømborg et al. 2006)
14 Assuming a linear relationship between the yield and CH4-emission and with a conventional dairy production set to 6 000 kg milk14 and the organic production to around 5 200 kg milk per cow per year.
15 The total consumption of milk in Norway is 1 500 million litres (Budsjettnemda for jordbruket 2009b)
16 Of about 1,5 kg CO2-eq (0.005 kg N2O ) per kg N together with about 3 kg CO2 from use of gas in the hydrogen production in total 4,5 kg CO2-eq per kg N (Yara)
17 We use 0.0269 kg N2O per kg mineral fertilizer N which includes the indirect contribution through evaporation to ammoniac and nitrogen run-off and direct contribution from N2O-N (Pettersen 2010). Trømborg et al. use 0.019 kg N2O per kg N.
17
have analysed the land use for the same production systems and food varieties as this resource is the main substitute through the use of the sun as an alternative energy source and land an alternative to among other mineral fertilizer and pesticides. The analyses of land use include both the land used to produce inputs outside Norway as well as for domestically produced inputs.
Such analyses are useful to identify key areas in food production systems to find more sustainable management strategies to improve environmental performance and lower the emissions of CO2-equivalents.
Statistics Norway provides knowledge about emissions from a sectoral view point18. This gives not an acceptable starting point for analysing possibilities for lowering CO2-emissions.
This is due to the fact that a good part of the emission related to production of food arises in other sectors. Comparing different food production systems must therefore include the emissions arising from the inputs (and outputs) from other sectors. The LCA methodology was therefore seen as appropriate as it has a product focus – tracing back from e.g. production of a kg of milk the emissions of CO2 as well as the land use under different production systems and methods.
We used data from NILFs FADN-farms (Driftsgranskningsbruk) modelled by Budsjettnemda for jordbruket to model farms (Referansebruk) representing different production systems.
whole farms we are able to track the substitution and the ‘lacking’ resource use due to integrated production processes.
The results show that for each of the products analysed wheat, milk and beef meat there are generally lower emissions from the organic production system than from the conventional system if we look at overall average numbers for different types of model farms. The average numbers for conventionally products are from 30% to 70% higher than for the organically products with the lowest difference for beef. There is however variation in the CO2-emission for each of the analysed products depending on type of production system. The CO2-emission from beef meat produced in combination with milk is only half the CO2-emission when produced from suckler cows where the emission is around 34 kg CO2-eq per kg beef meat.
In general the CO2-emission per kg food is much higher for the animal products than for the plant products, although the differences are reduced especially between meat and milk when the energy content of food is considered. The emission from meat is from 6 to 9 CO2-eq per kg kcal, from milk is around 4 CO2-eq per kg kcal, while production of wheat only contributes with from around 0.2 kg CO2-eq per kg kcal.
For land use, organically produced food has on average 10% to 70% higher use of land than conventional produced food with the lowest difference for beef. Within each type of production system the land use for animal products are higher than for plant products with around 16-17 m2 per kg kcal meat compared to around 1 m2 per kg kcal wheat.
The results show that there are relatively large emissions from mineral fertilizer which are not accounted for in the official estimates from the agricultural sectors. This implies among other that systems not using mineral fertilizer like organic farming systems show lower emissions
18 Norway: 50.8 mill tonnes CO2-eq in 2009 (Bye et al. 2009). Of these 9% (2008: 2.1 mill tonnes CH4 and 2.2 mill tonnes N2O) from agriculture (48% CH4, 41% N2O og 10% CO2). Methane (14 % from anaerobic storage of animal manure, 86% from ruminants).
18
measured per kg product. This was also considered by Trømborg et al. (2006), who corrected the official numbers for emission of climate gasses as calculated by Statistics Norway such that mineral fertilizer and carbon sequestration from moors and cultivated land were included.
This implied that the total emission from agriculture up to the farm gate was calculated to be roughly 7 799 000 tonnes CO2-eq in 2006.
The analyses carried out in this project and reported here shows that when comparing the emissions of CO2-equivalents for producing food one has to consider the sectors providing inputs to agriculture as these contribute with considerable emissions. Further it is important to consider the whole farm system when comparing production of food – and in this respect the model farms through FADN-data from NILF/Budsjettnemda for jordbruket have shown to be very useful. The use of land is of high importance to consider in comparison of the emission from different systems being the most important substitute for fossil energy. Our data material and the results provide therefore basis for analyses of different scenarios . E.g. Norway has excessive area for grassland and scenarios analysing substitution of imported protein with grass in changed feeding and management strategies for producing milk and meat may have political interest. The final choice for consumption of food can have very large impacts on the emissions of CO2-equivalents – as the differences between emissions from plant versus different animal products show. In NILF-discussion paper 2011-3 these issues are further elaborated using the results from this study.
References
o Andersson, K., Ohlsson, T., Olsson, P., 1998. Screening life cycle assessment (LCA) of tomato ketchup: a case study. Journal of Cleaner Production 6, 277– 288.
o Andersson, K., Ohlsson, T., 1999. Life cycle assessment of bread produced on different scales. Int J. LCA 4 (1), 25–40.
o Badgley, C., Moghtader, J., Quintero, E., Zakem, E., Chappell, M.J. and Aviles- Vazquez, K. 2007. Organic agriculture and the global food supply. Renewable Agriculture and Food Systems 22(2), 86-108.
o Bailey, A.P., Basford, W.D., Penlington, N., Park, J.R., Keatinge, J.D.H., Rehman, T., Tranter, R.B., Yates, C.M., 2003. A comparison of energy use in conventional and integrated arable farming systems in the UK. Agriculture Ecosystems &
Environment 97, 241–253.
o Baumann, H. and A. M. Tillman (2004). The Hitch Hiker's Guide to LCA - An orientation in life cycle assessment methodology and application. Lund, Sweden, Studentlitteratur.
o Berlin, J., 2002. Environmental life cycle assessment (LCA) of Swedish semi-hard cheese. Int. Dairy J. 12, 939–953.
o Brentrup F., J. Küsters, H. Kuhlmann, J. Lammel 2004. Environmental impact assessment of agricultural production systems using the life cycle assessment methodology I. Theoretical concept of a LCA method tailored to crop production, European Journal of Agronomy 20, 247–264
o Budsjettnemda for jordbruket 2008a. Referansebruksberegninger 2006. Beregninger basert på driftsgranskninga, avgitt juni 2008. www. Med tilhørende datamateriale o Budsjettnemda for jordbruket 2009a. Referansebruksberegninger 2007. Beregninger
basert på driftsgranskninga, avgitt juni 2009. For 2010, see:
http://www.nilf.no/Publikasjoner/BFJ/Bm/2010/ReferansebrukenePublikasjonen201 0.pdf
19
o Budsjettnemda for jordbruket 2007. Referansebruksberegninger 2005. Beregninger basert på driftsgranskninga, avgitt juni 2007. www. Med tilhørende datamateriale o Budsjettnemda for jordbruket 2006. Resultatkontrollen.
o Budsjettnemda for jordbruket 2008b. Totalkalkylen for jordbruket. Jordbrukets totalregnskap 2006 og 2007 og budsjett 2008.
o Budsjettnemda for jordbruket 2009b. Totalkalkylen for jordbruket. Jordbrukets totalregnskap 2007 og 2008 og budsjett 2009.
o Bye A.S., P. A. Aarstad, A. I. Løvberget, G. Berge and B. Hoem: Jordbruk og miljø:
Tilstand og utvikling 2010. Rapporter 48/2010. Statistisk sentralbyrå • Statistics Norway. Oslo–Kongsvinger ISBN 978-82-537-7973-7 Trykt versjon ISBN 978-82- 537-7974-4 Elektronisk versjon ISSN 0806-2056
o Carlsson-Kanyama A, Ekstrom MP, Shanathan H 2003. Food and life cycle energy inputs: consequences of diet and ways to increase efficiency. Ecological Economics 44, 293-307
o Casey, J.W., Holden, N.M., 2006. Greenhouse gas emissions from conventional, agri-environmental scheme, and organic Irish suckler-beef units. J. Environ. Qual.
35, 231–239.
o Cederberg, C., Mattsson, B., 2000. Life cycle assessment of milk production - a comparison of conventional and organic farming. J. Cleaner Prod. 8, 49–60.
o Cederberg, C., U. Sonesson, M. Henriksson, V. Sund, and J. Davis. 2009,
Greenhouse gas emissions from Swedish production of meat, milk and eggs 1990 and 2005. Göteborg: SIK, The Swedish Institute for Food and Biotechnology.
o Coley D., M. Howard, M. Winter M. 2009. Local food, food miles and carbon emissions: A comparison of farm shop and mass distribution approaches. Food Policy 34, 150-155
o Dalgaard, T., Halberg, N., Porter, J.R., 2001. A model for fossil energy use in Danish agriculture used to compare organic and conventional farming. Agriculture Ecosystems & Environment 87, 51–65
o Daly, H. E. and Cobb, J. B., Jr. 1989. For the Common Good. Redirecting the Economy Toward Community, the Environment, and a Sustainable Future. Beacon Press, Boston.
o De Boer, I.J.M., 2003. Environmental impact assessment of conventional and organic milk production. Livestock Production Science 80, 69–77.
o de Vries M., I.J.M. de Boer, Comparing environmental impacts for livestock products: A review of life cycle assessments, Livestock Science 128 (2010) 1–11 o Engström R, A Wadeskog, G Finnveden 2007. Environmental assessment of
Swedish agriculture, Ecological Economics, 60:550–563
o European Commission 2010: ILCD HandbookGeneral guide for life cycle assessment
o Eurostat. 2010. Using official statistics to calculate greenhouse gas emissions. A statistical guide. European Union. Luxembourg: Publications Office of the European Union, 2010. ISBN 978-92-79-14487-5. doi:10.2785/3842. Cat. No. KS-31-09-272- EN-C 2010 edition. http://epp.eurostat.ec.europa.eu/cache/ITY_OFFPUB/KS-31-09- 272/EN/KS-31-09-272-EN.PDF
o Financial Times 2010: Food Security Magazine
o Florén B, A Flysjö and K Lorentzon 2005. Ekologiska produktars miljönytta. SIK- rapport Nr 749 2006. SIK Institutet för livsmedel och bioteknikk. ISBN 91-7290- 248-5
o Forbrugerstyrelsen (Consumer Agency of Denmark), 1996. Impact on the
environment by the activities of a family. Copenhagen, Denmark (In Danish), 78
20
pp.Guinée, J. B. (2001). Life cycle assessment. An operational guide to the ISO standards. Final report. Den Haag, The Netherlands, Ministry of Housing, Spatial planning, and the Environment (VROM) and Centre of Environmental Science (CML).
o ISO (1997). 14040:1997. Environmental management - life cycle assessment - principles and framework. Geneva, Switzerland, International Organization for Standardization (ISO).
o ISO (2006). 14040:2006. Environmental management - Life cycle assessment - Principles and framework. Geneva, Switzerland, International Organization for Standardization (ISO).
o Jones, M. R. 1989. Analysis of the use of energy in agriculture. Approaches and Problems. Agricultural Systems 29, 339-355.
o Halberg N, Hayo HMG van der, Basset-Mens C, Dalgaard R & Boer IJM de (2005).
Environmental assessment tools for the evaluation and improvement of European livestock production systems. Livestock Production Science 96, 33-50
o Hall, C., Cleveland, A. S., Cutler J. and Kaufmann, R. K. (1992) Energy and Resource Quality: The Ecology of the Economic Process. University Press of Colorado, Colorado.
o Helsedirektoratet, 2008.
http://www.helsedirektoratet.no/publikasjoner/rapporter/utviklingen_i_norsk_kosthold_200 8__340054.pdf
o Hertwich E. 2005. Life cycle approaches to sustainable consumption: a critical review. Environmental Science and Technology 39, 4673-4684
o Hospido, Almudena, Jennifer Davis, Johanna Berlin, and Ulf Sonesson. “A review of methodological issues affecting LCA of novel food products.” The International Journal of Life Cycle Assessment 15, no. 1 (11, 2009): 44-52.
o http://faostat.fao.org/Portals/_Faostat/documents/pdf/world.pdf;http://faostat/Deskto pDefault.aspx?PageID=368&lang=en#ancor
o http://www.helsedirektoratet.no/publikasjoner/rapporter/utviklingen_i_norsk_kostho ld_2008__340054.pdf
o Hvid et al. 2004: Miljøvurdering af landbrugsprodukter. Miljøstyrelsen, Miljøprojekt nr. 954ISO (2006). 14040:2006. Environmental management - Life cycle assessment - Principles and framework. Geneva, Switzerland, International Organization for Standardization (ISO).
o Høgaas Eide, M., 2002. Life cycle assessment of industrial milk production. Int. J.
LCA 7 (1), 115–126.
o ISO 2006: ISO14040 Life cycle assessment
o Kemp K, Insch A, Holdsworth DK, Knigth JG 2010: Food miles: Do UK consumers actually care? Food Policy 35:504-513
o Klif 2010: Klimakur 2020 – tiltak og virkemidler for å nå norske klimamål mot 2020. TA 2590/2010.
o Korsaeth 2008. Relations between nitrogen leaching and food productivity in organic and conventional cropping systems in a long-term field study. Agriculture, Ecosystems and Environment 127:177–188
o Kramer, K.J., Biesiot, W., Kok., R., Wilting, H.C. and Schoot Uiterkamp, A.J.M.
1994. Energy counts. Possible energy savings of household spendings. IVEM- research re-port no. 71. Centre for Energy and Environmental Studies, University of Groningen, The Netherlands. (In Dutch, summary in English) 84 pp.Lampkin, N.H., 2003. From conversion payments to integrated action plans in the European Union.
21
In: OECD (Ed.), Organic Agriculture: Sustainability, Markets and Policies. CABI Publishing, Wallingford, pp. 313–328.
o Kramer, K.J., H. C. Moll, S. Nonhebel, H. C. Wilting 1999. Greenhouse gas emissions related to Dutch food consumption. Energy Policy 27 (4), 203-216 o Kramer, J.K., Ploeger, K., van Woerden, S., Ruijs, M., 2000. Environmental and
economic aspects of organic greenhouse vegetables in the Netherlands. In: Alföldi, T., et al. (Eds.), 13th International IFOAM Scientific Conference, 28–31 August 2000, Basel. vdf Hochschulverlag AG, 168 p.
o Lampkin, N.H., 2003. From conversion payments to integrated action plans in the European Union. In: OECD (Ed.), Organic Agriculture: Sustainability, Markets and Policies. CABI Publishing, Wallingford, pp. 313–328.
o Lötjönen, T., 2003. Machine work and energy consumption in organic farming.
Ecology and Farming, 7–8.
o Mattsson, B., 1999. Environmental Life Cycle Assessment (LCA) of Agricultural Food Production. Ph.D. Thesis. Swedish University of Agricultural Sciences, Alnarp. 298 p.
o Milà i Canals, L., Burnip, G.M., Suckling, D.M., Cowell, S.J., 2001. Comparative LCA of apple production in New Zealand und two production systems. In: Geerken, T., et al. (Eds.), Proceedings of the International Conference on LCA in Foods, 26–
27 April 2001, Gothenburg. SIK, VITO.
o McIntyre, B.D. H Herren, J Wakhungu and RT Watson (2009) IAASTD-report:
International Assessment of Agricultural Knowledge, Science and Technology for Development (2008). Global Report. ISBN 978-1-59726-538-6
www.agassessment.org and www.iaastd.net
o Meisterling Kyle, Constantine Samaras, Vanessa Schweizer, Decisions to reduce greenhouse gases from agriculture and product transport: LCA case study of organic and conventional wheat, Journal of Cleaner Production 17 (2009) 222–230
o Moilanen, P.-P., 1999. Elinkaari-inventaario ja ekotasetarkastelu
leipomoteollisuudessa. Lisensiaatintutkimus (Life Cycle Inventory and Ecobalance Method in Bakery Industry). Licentiate Examination. Tampere University of Technology, Department of environmental technology, Tampere, 131 pp. (in Finnish).
o Mondelaers Koen, Joris Aertsens and Guido Van Huylenbroeck, A meta-analysis of the differences in environmental impacts between organic and conventional farming, British Food Journal, 111(10), 2009, 1098-1119.
o Mouron, P., Scholz, R.W., Nemecek, T., Weber, O., 2006. Life cycle management on Swiss fruit farms: relating environmental and income indicators for
applegrowing. Ecological Economics 58, 561–578.
o Møller, H., Vold, M., 1995. Livsløpsanalyse ved kjøttproduksjon – En vurdering av svine – og lammekjøttproduksjon (Life Cycle Assessment of Meat Production, Assessment of Lamb and Pork Meat Production). Østfold Research Foundation, Fredrikstad. OR 53:95 (in Norwegian).
o Nemecek, T., Hugenin-Elie, O., Dubois, D., Gaillard, G., 2011. Life cycle assessment of Swiss farming systems: I. Integrated and organic farming.
Agricultural Systems 104, 217–232.
o Nemecek, T., Hugenin-Elie, O., Dubois, D., Gaillard, G., Schaller, B., Chervet, A., 2011. Life cycle assessment of Swiss farming systems: II. Extensive and intensive production. Agricultural Systems 104, 233–245.
o Neset T.S.S. and U. Lohm 2005. Spatial imprint of food consumption: A historical analysis for Sweden, 1870-2000. Human Ecology 33(4), 565-580
22
o Nguyen T.L.T., J.E. Hermansen and L. Mogensen 2010. Environmental
consequences of different beef production systems in the EU. Journal of Cleaner Production 18( 8), 756-766
o Pettersen J 2010. Direkteutslipp fra landbruket i LCA. Beregning av de direkte utslippene fra gårdsdrift og biogassanlegg, til bruk i livsløpsvurdering (LCA) av norsk landbruk. MiSA report no. 10/2010.
o Pimentel, D., Herdendorf, M., Eisenfeld, S., Olander, L., Carroquino, M., Corson, C., McDade, J., Chung, Y., Cannon, W., Roberts, J., Bluman, L. and Gregg, J. 1994.
Achieving a secure energy: environmental and economic issues. Ecological Economics 9, 201-219.
o Pimentel, D., Hepperly, P. and Seidel, R., 2005. Environmental, energetic, and economic comparisons of organic and conventional farming systems, Bioscience 55(7), 573-83.
o Pretty, J. N., A. S Ball, T. Lang, and J. I. L. Morison, 2005. Farm costs and food miles: An assessment of the full cost of the UK weekly food basket. Food Policy 30(1) , 1–19.
o Refsgaard, K., Halberg, N., Kristensen, E.S., 1998. Energy utilization in crop and dairy production in organic and conventional livestock production systems.
Agricultural Systems 57, 599–630.
o Rossier, D., Gaillard, G., 2001. Bilan écologique de l’exploitation agricole: Méthode et application à 50 entreprises. Forschungsanstalt für Agrarökologie und Landbau (FAL), Zürich, 176 p.
o Roy P, Nei D, Orikasa T, Xu Q, Okadome H, Nakamura N, Shiina T., 2009. A review of life cycle assessment (LCA) on some food products. Journal of Food Engineering 90, 1–10
o Sandmo Trond (ed.), 2009: The Norwegian emission inventory 2009. Documentation of methodologies for estimating emissions of greenhouse gases and long-range transboundary air pollutants. Statistics Norway, Oslo, Norway.”
o Saunders C., A. Barber and G.Taylor, 2006. Food Miles – Comparative
Energy/Emissions Performance of New Zealand’s Agriculture Industry, Research Report No. 285, Agribusiness & Economics Research Unit , Lincoln University, New Zealand
o Statistics Norway Forbruksundersøkelse 2005-2007
o Statistics Norway, 2009. http://www.ssb.no/emner/01/05/40/avfregno/
o Statistics Norway 2010: http://www.ssb.no/emner/01/04/10/klimagassn/tab-2010- 05-19-05.html Accessed 9. August 2011.
o Sundt, P., 2010. Matavfall, avfallsforebygging og emballasjeoptimering – EMMA.
Mepex Consult og Østfoldforskning.
o Svendgård-Stokke, Siri 2011. Tilgjengelige arealressurser for økt matproduksjon.
Kornkonferansen 2011. Felleskjøpet.
o Swensen B 2010. Økologisk jordbruk og klima. Oikos-rapport 2-1010.
o Trømborg et al. 2008 er med i referanseliste men ikke 2006 og 2005, heller ikke Swensen et al., 2010
o Trømborg, E., Nielsen, A. og Hoen, H.F. (eds) 2008. Klimagasser og bioenergi fra landbruket – kunnskapsstatus og forskningsbehov. INA fagrapport 11. ISSN 1503- 9439.
o Tukker, A., Huppes, G., Guine´e, J., Heijungs, R., de Koning, A., van Oers, L., Suh, S., Geerken, T., Van Holderbeke, M., Jansen, B., Nielsen, P., 2005. Environmental Impact of Products (EIPRO). Analysis of the Life Cycle Environmental Impacts
23
Related to the Total Final Consumption of the EU25. Full Draft Report. Institute for Prospective Technological Studies (IPTS), 29 April 2005, 117 pp.
o Tukker, A. and B. Jansen. 2006. Environmental impacts of products: A detailed review of studies. Journal of Industrial Ecology 10(3): 159–182.
o Tukker, A., P. Eder, and S. Suh. 2006b. Environmental impacts of products: Policy relevant information and data challenges. Journal of Industrial Ecology 10(3): 183–
198.
o Usva K, Saarinen M, Katajajuuri J-M, Kurppa S (2009) Supply chain integrated LCA approach to assess environmental impacts of food production in Finland.
Agricultural and Food Science, 18:460–476
o van der Werf, H.M.G., Kanyarushoki, C., Corson, M.S., 2009. An operational method for the evaluation of resource use and environmental impacts of dairy farms by life cycle assessment. Journal of Environmental Management 90, 3643–3652.
o Watson, R., Zinyowera, M., Moss, R., Dokken, D. (Eds.) 1996. Climate Change 1995: Impacts, Adaptations, and Mitigation of Climate Change: Scientific-Technical Analyses. Cambridge University Press, Cambridge, UK.
o Watson C.A., Walker R.L. and Stockdale E.A. 2008. Research in organic production systems – past, present and future. Journal of Agricultural Science 146, 1-19
o Weidema, B.P., Pedersen, R.L., Drivsholm, T.S., 1995. Life Cycle Screening of Food Products – Two Examples and Some Methodological Proposals. Danish Academy of Technical Sciences, Copenhagen, Denmark, 193 pp.
o Weidema BP, M Wesnæs, J Hermansen, T Kristensen and N Halberg 2008. (Eder P and L Delgado (eds)). Environmental Improvement Potentials of Meat and Dairy Products. Institute for Prospective Technological Studies. JRC European
Commission. EU 23491 EN-2008. ISBN 978-92-79-09716-4 ISSN 1018-5593 DOI 10.2791/38863 Wenzel, H., M. Hauschild, et al. (1997). Environmental assessment of products. Volume 1: Methdology, tools and case studies in product development.
London, UK, Chapmann & Hall.
o Williams, A. G., E. Audsley og D. L. Sandars 2006: Determining the environmental burdens and resource use in the production of agricultural and horticultural
commodities. Defra project report IS0205.
o World Health Organization (WHO) and FAO data,
www.who.int/nutrition/topics/3_foodconsumption/en/index.html;
o www.LCAfood.dk
o Ziegler, F., Nilsson, P., Mattsson, B., Walther, Y., 2003. Life cycle assessment of frozen cod fillets including fishery specific environmental impacts. Int. J. LCA 8 (1), 39–47.
